Fuzzball Shadows: Emergent Horizons from Microstructure

TL;DR

This paper investigates fuzzball geometries in string theory, showing how their microstructure can produce shadows similar to black holes, offering potential observational tests to distinguish them from traditional black holes.

Contribution

It demonstrates that fuzzball microstructures can create black-hole-like shadows, providing a new way to differentiate fuzzballs from classical black holes through observational signatures.

Findings

Fuzzball shadows resemble black hole shadows in the scaling limit.

Microstructure traps light, creating long-lived chaotic orbits.

Shadow size and residual glow can distinguish fuzzballs from other models.

Abstract

We study the physical properties of four-dimensional, string-theoretical, horizonless "fuzzball" geometries by imaging their shadows. Their microstructure traps light rays straying near the would-be horizon on long-lived, highly redshifted chaotic orbits. In fuzzballs sufficiently near the scaling limit this creates a shadow much like that of a black hole, while avoiding the paradoxes associated with an event horizon. Observations of the shadow size and residual glow can potentially discriminate between fuzzballs away from the scaling limit and alternative models of black compact objects.